Technical Field
The present disclosure relates to a power storage device capable of being bent or curved and realizing a high capacity, and also relates to a production method thereof.
Description of the Related Art
The following description of related art sets forth the inventor's knowledge of related art and certain problems therein and should not be construed as an admission of knowledge in the prior art.
In accordance with thinning and lightweighting of a mobile device, such as, e.g., a smart phone and a tablet terminal, as an external member for a lithium-ion secondary battery or a lithium-polymer secondary battery to be mounted on the mobile device, in place of a conventional metallic can, a laminated external member in which resin films are adhered on both surfaces of a metal foil is used. Similarly, it is being considered to mount an electrical condenser, a capacitor, etc., using a laminated external member on an IC card or an electronic device as a backup power source.
Further, in recent years, along with an increase in size of a smart phone or a tablet terminal, it is being considered to make a device itself bendable, and also in a wearable electronic device represented by a smart watch and a smart glass, it is being considered to mount a small and lightweight laminate battery using a laminate external member.
In order to make a smart phone or a tablet terminal bendable, it is required to make various electronic devices including batteries flexible against bending, curving, etc., in addition to make the casing of such a device flexible. Further, even in an electronic device, such as, e.g., a wearable electronic device, etc., to be fitted on a human body, it is required to make various electronic devices such as batteries flexible.
As a device causing no problem even if the battery is bent as mentioned above, it is proposed to use a thin sheet-type battery (see Japanese Unexamined Laid-open Patent Application Publication No. 2000-173559 (hereinafter referred to as “Patent Document 1”), International Publication No. 2012/140709 pamphlet (WO2012/140709) (hereinafter referred to as “Patent Document 2”).
However, in a thin sheet-like battery which is reduced in thickness to secure the flexibility, the number of stacking electrodes decreases and the electron accumulation layer such as an active material becomes thin, resulting in a reduced electric capacity. As a result, mounting such a battery on an electronic device causes a problem that the charge-discharge cycle becomes short. In order to increase a capacity of a battery, there is no option but to increase the number of stacking electrodes or increase the size of the electrode. However, in the former structure, the battery cannot be curved or bent. On the other hand, in the latter structure, the size of the battery becomes large, which limits devices capable of mounting such a large battery.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. For example, certain features of the preferred described embodiments of the invention may be capable of overcoming certain disadvantages and/or providing certain advantages, such as, e.g., disadvantages and/or advantages discussed herein, while retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.